Cystic fibrosis (CF) is the most common lethal recessive genetic disorder in the Caucasian population of North America. The cystic fibrosis transmembrane conductance regulator (CFTR) gene, which encodes the cystic fibrosis gene product, was cloned in 1989. Since that time, rapid progress has been made in the expression of recombinant CFTR using retroviral and adenoviral vectors, in vitro and in vivo. Approaches to somatic gene therapy directed at the pulmonary manifestations of CF are being actively pursued in several laboratories. We propose to evaluate the delivery of heterologous CFTR to the airways of experimental animals, using retroviral and adenoviral vectors. Preliminary studies will be performed using beta-galactosidase expression vectors, to assess the number and types of cells expressing recombinant protein and the duration of that expression for each vector type. We will focus on the use of retroviral vectors in newborn animals, and the use of oxygen exposure as a stimulus to epithelial proliferation in conjunction with these vectors in older animals. We also propose to create a transgenic mouse expressing human CFTR under the control of an intestine-specific promotor. This mouse, when bred to CFTR mutant mice present in our laboratory, should yield an animal with diminished intestinal stigmata of CF, able to survive long enough to demonstrate the pulmonary manifestations of the disease. Such mice will be exposed to retroviral and adenoviral constructs bearing CFTR, and studied for evidence of phenotypic alleviation of their pulmonary disease. These manifestations can also be studied in the context of epithelial damage to the airway from oxygen exposure or respiratory viral infection, to enhance the manifestations of the pulmonary phenotype in situations which mimic those encountered by human CF patients. Administration of adenoviral constructs by aerosol will be evaluated in conjunction with Dr. Knight. Finally, we propose to investigate the incorporation of putative mammalian replication origins and of the Epstein-Barr virus origin of replication into adenoviral vectors to enhance the persistence of expression of heterologous genes introduced by these vectors.